Optoelectronic devices such as laser diodes for optical transceivers can be efficiently fabricated using wafer processing techniques. Generally, wafer processing techniques simultaneously form a large number (e.g., thousands) of devices on a wafer. The wafer is then sawed or cut to separate individual chips. Simultaneous fabrication of a large number of chips keeps the cost per chip low, but each individual chip must be packaged and/or assembled into a system that protects the chip and provides both electrical and optical interfaces for use of the devices on the chip.
Assembly of a package or a system containing an optoelectronic device is often costly because of the need to align multiple optical components with the semiconductor device. For example, the transmitting side of an optical transceiver chip may include a vertical cavity surface emitting laser (VCSEL) that emits an optical signal in a direction perpendicular to the face of the VCSEL. A lens or other optical element is typically necessary to focus or alter the optical signal from the laser and improve coupling of the optical signal into an external optical fiber. The laser, the lens, and an optical fiber can be aligned during an assembly process that produces an optical subassembly (OSA). The alignment process can be a time consuming/expensive process that involves adjusting the relative position of the laser while measuring the optical power coupled into the fiber. The relative positions of the laser, lens, and optical fiber are locked once optical coupling efficiency is at a maximum or acceptable level. Mechanisms for adjusting and locking the relative position of the laser can increase the cost and complexity of an OSA. Further, the alignment and assembly processes generally must be performed separately for each package.
Wafer-level packaging is a promising technology for reducing the size and the cost of the packaging of optoelectronic devices. With wafer-level packaging, components that conventionally have been separately formed and attached are instead fabricated on a wafer that corresponds to multiple packages. The resulting structure can be sawed or cut to separate individual packages. Packaging techniques and structures that can reduce the size and/or cost of packaged optoelectronic devices are sought.